Device for guiding a fuel assembly during loading

Abstract

The guiding device comprises a body, the size of which corresponds to that of a fuel assembly, intended to rest on the lower core plate (20), equipped with holding means intended to be grasped by an assembly-handling machine, extended downwards by means (18) for positioning it on the lower core plate at an assembly location adjacent to the one intended to receive the assembly to be guided, and two wings (30) carried by the bottom part of the body, forming an angle of 90° in a horizontal plane, each one having an inclined guide face (32) ending at the bottom above the location intended to receive the assembly when the device is in place. Each wing (30) can be retracted, starting from a deployed state, towards a position in which it is withdrawn within the horizontal size of the body.

We claim: 
     
       1. Device for guiding a fuel assembly during loading into a predetermined fuel assembly location on a nuclear reactor lower core plate, comprising: a body having a transverse cross-section substantially identical to a transverse cross-section of a fuel assembly, suitable to rest on the lower core plate, holding means on said body for being grasped by a fuel assembly handling machine, and indexing means extending downwardly from the body for positioning said body on the lower core plate at an assembly location adjacent to the assembly location intended to receive the fuel assembly to be guided, and   two wings carried by a lower part of said body, retractable from a deployed state in which they form an angle of 90° in a horizontal plane into a position in which they are within the transverse cross-section of the body, each said wing having a face which is inclined guide face and has a downward end above the location intended to receive the assembly when the device is in place and said wings are deployed.   
     
     
       2. Device according to claim 1, wherein each of said wing is pivotably mounted on a pin allowing it to move between said deployed position and said withdrawn position through an opening formed in a lateral wall of said body. 
     
     
       3. Device according to claim 2, wherein said pin is arranged so that the wing is based by its weight into the deployed position. 
     
     
       4. Device according to claim 2, wherein a dihedron-shaped indentation is formed in said body at a location which is straddled by the two wings when the latter are in deployed state and wherein each said pin is located on said body in a direction such that it slopes downwards from an inside towards an outside of the body, and converges toward the respective lateral wall from the location of said indentation. 
     
     
       5. Device according to claim 1, further comprising means in said body which are vertically displaceable within the body between: a bottom position into which they are biased by gravity or by a spring and where they keep said wings in the withdrawn position thereof, and   a top position into which they are forced by abutment against the lower core plate and in which they allow the wings to pivot to their deployed position.   
     
     
       6. Device according to claim 5, wherein said means include a unit slidably mounted on at least one vertical rod fixed to said body and arranged to bear a pair of rollers each carried by a respective one of said wings, and vertical rods projecting from said unit for abutment against centering fingers belonging to the lower core plate when the device is set down on the lower core plate. 
     
     
       7. Device according to claim 1, further comprising adjustable stop means for limiting the displacement of each of said wings. 
     
     
       8. Device according to claim 1, further comprising spindle means slidably received in the body for retaining the wings in the retracted position thereof, when located in a predetermined position. 
     
     
       9. Device according to claim 1, wherein said body is formed with an indentation constituting a 90°-reentrant dihedron, located between the two wings, and having a shoulder part in a region of the wings, said shoulder having inclined faces which are so located as to constitute an extension of the guide faces of the wings when the latter are in the deployed position. 
     
     
       10. Device according to claim 9, wherein said body comprises an upper part and a lower part, both of square cross section, fixed to one another, and wherein the indentation has a cross-section in the upper part representing approximately one quarter of the square cross-section and ends downwardly as sloped surfaces merging with a smaller cross-section of the indentation in the lower part.